Fix known typos

Sweep the codebase for common typos. Includes some changes to visible function
names that were misspelt.

llvm-svn: 200018
diff --git a/llvm/test/CodeGen/SystemZ/int-cmp-45.ll b/llvm/test/CodeGen/SystemZ/int-cmp-45.ll
index 753a528..9c9c49c 100644
--- a/llvm/test/CodeGen/SystemZ/int-cmp-45.ll
+++ b/llvm/test/CodeGen/SystemZ/int-cmp-45.ll
@@ -1,4 +1,4 @@
-; Test that compares are ommitted if CC already has the right value
+; Test that compares are omitted if CC already has the right value
 ; (z196 version).
 ;
 ; RUN: llc < %s -mtriple=s390x-linux-gnu -mcpu=z196 | FileCheck %s